A designed peptide targeting CXCR4 displays anti-acute myelocytic leukemia activity in vitro and in vivo.

Li X, Guo H, Yang Y, Meng J, Liu J, Wang C, Xu H - Sci Rep (2014)

Bottom Line:
We show that E5 has high affinity to multiple AML cells with high CXCR4 level in a concentration dependent manner.E5 can induce concentration-dependent apoptosis in the four AML cell lines tested while did not affect the viability of MS-5 or human umbilical vein cell (ea.hy926) even at 80 µM, both of which have a low level of CXCR4.In vivo experimental results show that immunocompromised mice transplanted with HL-60 cells survived longer when treated with E5 twice a week in comparison to those treated with cyclophosphamide.

ABSTRACTLeukemia cells highly expressing chemokine receptor CXCR4 can actively response to stroma derived factor 1α (CXCL12), trafficking and homing to the marrow microenvironment, which causes poor prognosis and relapse. Here we demonstrate that a novel designed peptide (E5) targeting CXCR4 inhibits CXCL12- and stroma-induced activation in multiple acute myelocytic leukemia (AML) cell lines and displays anti-AML activity. We show that E5 has high affinity to multiple AML cells with high CXCR4 level in a concentration dependent manner. E5 significantly inhibits CXCL12- or murine stromal cell (MS-5)-induced migration of leukemia cells and prevents the cells from adhering to stromal cells. Mechanistic studies demonstrate that E5 down-regulates CXCL12-induced phosphorylation of Akt, Erk, and p38, which affects the cytoskeleton F-actin organization and ultimately results in the inhibition of CXCL12- and stroma-mediated leukemia cell responses. E5 can induce concentration-dependent apoptosis in the four AML cell lines tested while did not affect the viability of MS-5 or human umbilical vein cell (ea.hy926) even at 80 µM, both of which have a low level of CXCR4. In vivo experimental results show that immunocompromised mice transplanted with HL-60 cells survived longer when treated with E5 twice a week in comparison to those treated with cyclophosphamide.

f4: The inhibitory effect of E5 on the MS-5-mediated adhesion of multiple leukemia cell lines.MS-5 cells were seeded in the culture well to form a stromal cell layer. (a) The percentage of adhering leukemia cells on the MS-5 layer. The leukemia cells were pretreated with E5 at different concentrations. (b) Typical images of adhering NB4 cells pretreated with E5 at different concentrations. Leukemia cells were stained with calcein-AM (green). Data are presented as mean ± SD (n = 3). The * represents significant difference from sample groups to the control group (*: p < 0.05, **: p < 0.01).

Mentions:
It is well known that CXCL12 secreted by non-malignant stromal cells recruits leukemia cells to bone marrow. The recruited cells subsequently adhere to marrow stromal cells293031. Direct cell interactions with bone marrow microenvironment components can provide survival, anti-apoptosis and drug resistance signals to the leukemia cells1332. Hence we next investigated whether E5 interferes with the adhesive interaction between MS-5 and leukemia cells. Results clearly show that E5 significantly reduced the number of cells adhering to the MS-5 cell layer in a concentration dependent way in the four cell lines. The strongest inhibitory effect of E5 on the cell adhesion was reached to 36%, 59%, 49% and 63% for HL-60, NB4, THP-1 and U937 respectively. In the comparison, E5 more strongly inhibited the adhesion of NB4 and U937 among the four cell lines at 10 µM (Fig. 4).

f4: The inhibitory effect of E5 on the MS-5-mediated adhesion of multiple leukemia cell lines.MS-5 cells were seeded in the culture well to form a stromal cell layer. (a) The percentage of adhering leukemia cells on the MS-5 layer. The leukemia cells were pretreated with E5 at different concentrations. (b) Typical images of adhering NB4 cells pretreated with E5 at different concentrations. Leukemia cells were stained with calcein-AM (green). Data are presented as mean ± SD (n = 3). The * represents significant difference from sample groups to the control group (*: p < 0.05, **: p < 0.01).

Mentions:
It is well known that CXCL12 secreted by non-malignant stromal cells recruits leukemia cells to bone marrow. The recruited cells subsequently adhere to marrow stromal cells293031. Direct cell interactions with bone marrow microenvironment components can provide survival, anti-apoptosis and drug resistance signals to the leukemia cells1332. Hence we next investigated whether E5 interferes with the adhesive interaction between MS-5 and leukemia cells. Results clearly show that E5 significantly reduced the number of cells adhering to the MS-5 cell layer in a concentration dependent way in the four cell lines. The strongest inhibitory effect of E5 on the cell adhesion was reached to 36%, 59%, 49% and 63% for HL-60, NB4, THP-1 and U937 respectively. In the comparison, E5 more strongly inhibited the adhesion of NB4 and U937 among the four cell lines at 10 µM (Fig. 4).

Bottom Line:
We show that E5 has high affinity to multiple AML cells with high CXCR4 level in a concentration dependent manner.E5 can induce concentration-dependent apoptosis in the four AML cell lines tested while did not affect the viability of MS-5 or human umbilical vein cell (ea.hy926) even at 80 µM, both of which have a low level of CXCR4.In vivo experimental results show that immunocompromised mice transplanted with HL-60 cells survived longer when treated with E5 twice a week in comparison to those treated with cyclophosphamide.

ABSTRACTLeukemia cells highly expressing chemokine receptor CXCR4 can actively response to stroma derived factor 1α (CXCL12), trafficking and homing to the marrow microenvironment, which causes poor prognosis and relapse. Here we demonstrate that a novel designed peptide (E5) targeting CXCR4 inhibits CXCL12- and stroma-induced activation in multiple acute myelocytic leukemia (AML) cell lines and displays anti-AML activity. We show that E5 has high affinity to multiple AML cells with high CXCR4 level in a concentration dependent manner. E5 significantly inhibits CXCL12- or murine stromal cell (MS-5)-induced migration of leukemia cells and prevents the cells from adhering to stromal cells. Mechanistic studies demonstrate that E5 down-regulates CXCL12-induced phosphorylation of Akt, Erk, and p38, which affects the cytoskeleton F-actin organization and ultimately results in the inhibition of CXCL12- and stroma-mediated leukemia cell responses. E5 can induce concentration-dependent apoptosis in the four AML cell lines tested while did not affect the viability of MS-5 or human umbilical vein cell (ea.hy926) even at 80 µM, both of which have a low level of CXCR4. In vivo experimental results show that immunocompromised mice transplanted with HL-60 cells survived longer when treated with E5 twice a week in comparison to those treated with cyclophosphamide.